Modelling the effect of temperature and water activity in the growth boundaries of Aspergillus flavus isolates

ASTORECA A.; VAAMONDE G.; DALCERO A.; RAMOS A.; MARIN S.

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 156 p. 60 - 67

0168-1605

The aim of this study was to model the effects of temperature (10-40 ºC) and aw (0.80-0.98), in two media (Czapek yeast agar: CYA; corn extract medium: CEM) on the growth rates and growth boundaries (growth-no growth interface) of three A. flavus isolated from corn in Argentina. Both kinetic and probability models were applied to colony growth data. The growth rates obtained in CYA were significantly (p<0.05) greater than those obtained in CEM medium. No significant differences (p<0.05) were observed among the three isolates. The growth rate data showed good fitting to the Rosso cardinal models combined with the gamma-concept with R2=0.98-0.99 and RMSE=0.60-0.78, depending on media and isolates. Regarding the probability model, it allowed predicting safe storage (p of growth <0.01) for one month of moist maize (e.g. 0.90 aw) as long as temperature is under 15 ºC, or of dry maize (e.g. 0.80 aw) as long as temperature is under 27 ºC. Storage at <0.77 aw would be safe regardless of the storage temperature. Probability models allow evaluating the risk of fungal contamination in the process of storage, so the results obtained in this study may be useful for application in systems of food safety management